derive various impls instead of hand-rolling them

[oli-obk]

r? @lcnr

This may not have been what you asked for in 964b97e#r84051418 but I got carried away while following the compiler team meeting today.

[rustbot]

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

[lcnr]

it's better than what i've asked for 😁

one more idea, with or without it

r=me

[oli-obk]

@bors r=lcnr p=1 bitrotty

[bors]

📌 Commit c6fcb1c has been approved by lcnr

It is now in the queue for this repository.

[bors]

⌛ Testing commit c6fcb1c with merge df34db9...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing df34db9 to master...

[rust-timer]

Finished benchmarking commit (df34db9): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	1.2%	[0.2%, 2.2%]	11
Regressions ❌ (secondary)	0.9%	[0.3%, 2.1%]	18
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.7%	[-0.9%, -0.5%]	6
All ❌✅ (primary)	1.2%	[0.2%, 2.2%]	11

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	3.4%	[3.4%, 3.4%]	1
Regressions ❌ (secondary)	4.3%	[3.5%, 5.1%]	2
Improvements ✅ (primary)	-3.6%	[-3.6%, -3.6%]	1
Improvements ✅ (secondary)	-4.5%	[-4.5%, -4.5%]	1
All ❌✅ (primary)	-0.1%	[-3.6%, 3.4%]	2

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.9%	[2.7%, 5.1%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-2.6%, -2.6%]	1
All ❌✅ (primary)	-	-	0

Footnotes

1. the arithmetic mean of the percent change ↩ ↩² ↩³

2. number of relevant changes ↩ ↩² ↩³

[nnethercote]

Looks like some genuine regressions.

@oli-obk: how do the derived version differ from the hand-written ones? Type folding is typically quite hot, so small differences could easily have perf effects.

[oli-obk]

I'll look into them. Most should be equivalent, I did check beforehand

[oli-obk]

From the following diff I'm guessing that this PR caused some additional obligations to be generated or just processed.

139,443,901  ???:<rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
 61,282,965  ???:<rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty
-59,795,752  ???:<alloc::rc::Rc<rustc_middle::traits::ObligationCauseCode> as core::ops::drop::Drop>::drop
 49,456,068  ???:<rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::FallibleTypeFolder>::try_fold_ty
-47,967,367  ???:<rustc_middle::ty::Ty as rustc_middle::ty::fold::TypeSuperFoldable>::super_fold_with::<rustc_middle::ty::subst::SubstFolder>
 46,111,073  ???:<rustc_trait_selection::traits::select::SelectionContext>::evaluate_predicates_recursively::<alloc::vec::into_iter::IntoIter<rustc_infer::traits::Obligation<rustc_middle::ty::Predicate>>>
 44,568,113  ???:<rustc_infer::infer::combine::CombineFields>::instantiate
 33,973,909  ???:<rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::register_predicate_obligation
-31,618,494  ???:<rustc_infer::infer::equate::Equate as rustc_middle::ty::relate::TypeRelation>::relate::<rustc_middle::ty::Ty>
 30,370,709  ???:<rustc_trait_selection::traits::wf::WfPredicates>::nominal_obligations_inner
 29,798,110  ???:rustc_trait_selection::traits::wf::predicate_obligations
 26,729,122  ???:<rustc_trait_selection::traits::select::SelectionContext>::assemble_candidates
 25,095,611  ???:<rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_infer::infer::InferOk<(alloc::vec::Vec<rustc_middle::ty::adjustment::Adjustment>, rustc_middle::ty::Ty)>, rustc_middle::ty::error::TypeError, <rustc_typeck::check::fn_ctxt::FnCtxt>::try_coerce::{closure
-24,951,977  ???:<rustc_trait_selection::traits::select::SelectionContext>::evaluate_predicate_recursively
-23,810,814  ???:<rustc_typeck::check::coercion::Coerce>::coerce
 23,372,325  ???:<rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::ProvePredicate> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
 20,236,839  ???:<alloc::vec::Vec<rustc_infer::traits::Obligation<rustc_middle::ty::Predicate>> as alloc::vec::spec_from_iter::SpecFromIter<rustc_infer::traits::Obligation<rustc_middle::ty::Predicate>, core::iter::adapters::filter::Filter<core::iter::adapters::map::Map<core::iter::adapters::zip::Zip<core::iter::adapters::zip::Zip<alloc::vec::into_iter::IntoIter<rustc_middle::ty::Predicate>, alloc::vec::into_iter::IntoIter<rustc_span::span_encoding::Span>>, core::iter::adapters::rev::Rev<alloc::vec::into_iter::IntoIter<rustc_span::def_id::DefId>>>, <rustc_trait_selection::traits::wf::WfPredicates>::nominal_obligations_inner::{closure
 17,899,560  ???:<rustc_trait_selection::traits::select::SelectionContext>::select

[bjorn3]

@oli-obk This PR seems to have regressed the lift impl for Instance. cg_clif depends on it for it's jit mode.

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/driver/jit.rs:239:59
stack backtrace:
   0: rust_begin_unwind
             at /rustc/2019147c5642c08cdb9ad4cacd97dd1fa4ffa701/library/std/src/panicking.rs:584:5
   1: core::panicking::panic_fmt
             at /rustc/2019147c5642c08cdb9ad4cacd97dd1fa4ffa701/library/core/src/panicking.rs:142:14
   2: core::panicking::panic
             at /rustc/2019147c5642c08cdb9ad4cacd97dd1fa4ffa701/library/core/src/panicking.rs:48:5
   3: rustc_codegen_cranelift::driver::jit::jit_fn
   4: rustc_codegen_cranelift::driver::jit::run_jit

The Instance for which it fails is Instance { def: Item(WithOptConstParam { did: DefId(0:61 ~ mini_core_hello_world[7ee4]::main), const_param_did: None }), substs: [] }.

[oli-obk]

oh... this is wrong now 🤦